Scraper or grader



Feb. 7, 1939. c, BUFFlNGTON Re. 20,996

SCRAPER OR GRADER Original Filed June 2, 1933 5 Sheets-Sheet 1 f/ar'y a Bea /17196011.

strewn 11.9

Feb. 7, 1939. H c BUFFINGTON Re. 20,996

SCRAPER OR HEADER Original Filed June 2, 1935 5 Sheets-Sheet iuulnml Feb. 7, 1939. BUFFINGTON Re. 20,996

SCRAPER OR GRADER Original Filed June 2. 1933 5 Sheets-Sheet 3 Fig. 3.

IIIIIlIl'ITI v Feb. 7, 1939. H c. BUFFINGTON S CRAPER OR GRADER Original Filed June 2,

1933 5 Sheets-Sheet 4 Feb. 7, 1939.

H. c. BUFFINGTON Re. 20,996

SCRAPER OR GRADER Original Filed June 2, 1933 5 Sheets-Sheet 5 59 0/1. LOCKO a owtkuvs Reissued Feb. 7, 1939 UNITED STATES PATENT OFFICE The Baker Manufacturing Company,

Springfield, III., a corporation of Illinois Original No. 2,044,933, dated June 23, 1936, Serial No. 674.111, June 2, 1933. Application for reissue May 2, 1938, Serial No. 205,526

29 Claims.

My invention relates to new and useful improvements in scrapers or graders and to what has become generally known in the art as a bulldozer, the principal object of the invention residing in the provision of novel means for mounting the bulldozer on a tractor of the well-known crawler or endless track type and for raising and lowering the same into inoperative or operative position.

Another object of the invention consists in the provision of means whereby the scraping blade or mold board blade of the bulldozer is always kept in perfect alignment with the ground line when the tractor is going over uneven ground.

A further object resides in so connecting the bulldozer to the tractor that the weight thereof is equally distributed on both tracks of the tractor.

Still another object of the invention consists in the provision of hydraulic means for raising and lowering the bulldozer, such hydraulic means permitting, when desired. the scraping blade or mold board blade to be forced into tight contact with the ground and held in such position against 5 raising movement during the operation of the tractor, or when desired permitting what might be termed a floating action of the blade or in other words permitting the blade to raise and lower due to unevenness in the ground.

With the above and other objects in view, which will appear as the description proceeds, my invention consists in the novel details of construction, and arrangement of parts, described in the following specification and illustrated in the accompanying drawings, and while I have illustrated and described the preferred embodiments of the invention, as they now appear to me. it will be understood that such changes may be made as will fall within the scope of the ap- 40 pended claims.

In the drawings:-

Fig. 1 is a side elevation showing the bulldozer mounted on a tractor and in raised position.

- Fig. 2 is a view similar to Fig. 1 showing the bulldozer in lowered position.

Fig. 3 is a rear elevation.

Fig. 4 is a fragmental sectional detail taken on the line 44 of Fig. 5.

Fig. 5 is a fragmental sectional detail taken on the line 5-5 of Fig. 4.

Fig. 6 is a. fragmentai detail showing in side elevation the pivotal mounting for the bulldozer and the brackets secured to the track frame, for mounting the cylinder of the raising and lowermg mechanism.

Fig. 7 is a fragmental top plan of the construction shown in Fig. 6 with a portion of the push beam shown in top plan and pivotally connected to the bulldozer mounting.

Fig. 8 is a transverse section on the line 88 of 5 Fig. '7.

Fig. 9 is a transverse section on the line 9-9 of Fig. 7.

Fig. 10 is a. transverse section on the line |0Ill of Fig. 7. 10

Fig. 11 is a fragmental side elevation, with parts in longitudinal section, showing the tank for containing the oil used in the mechanism for raising and lowering the bulldozer, the pump for circulating the oil, one of the lowering and elel5 vating cylinders, the connecting mechanism for conveying the oil to the lowering and elevating cylinder, and the valve for controlling the oil circulation and the operating lever therefor.

Fig. 12 is a fragmental detail showing an end 20 view of the oil tank, the pipe and valve connections, and control lever for the valve; and

Fig. 13 is a section on the line i3-|3 of Fig. 12.

In the drawings A denotes a tractor of the crawler or endless track type including the track frames B and endless tracks C of usual wellknown construction and as the driving mechanism for the endless tracks, nor the mounting therefor, form no particular part of the present invention a detailed description thereof is not thought necessary. At D I have illustrated a seat for the operator and it will be understood that the control levers for the operation of the tractor will be within easy reach as will also the control lever or handle for operating the valve of the raising and lowering mechanism for the bulldozer. The track frames are pivotally mounted, adjacent their rear ends on the axle E in the usual well-known manner and at the forward ends are connected to a transversely extending spring F as is the custom in tractors of the type illustrated. With this construction the forward ends of the track frames and tracks may raise and lower while going over uneven ground and one track frame and its associated track may swing on its pivot independent of the other.

My improved form of bulldozer, which is carried by the tractor, includes the brackets I which are secured to the outer faces of the tracks 18, each of these brackets including a forwardly directed portion indicated at 2 and provided with an opening 3 to receive the pivot pin 4 carried by the plate 5. Pivotally connected to the brackets i by the pins 4 are the side push beams 6 which are of hollow formation as shown more 5 particularly in Fig. 8 of the drawings, these push beams being formed of the side plates I each of which has along its longitudinal edges an inwardly directed flange 3, the meeting edges of the flanges being welded as shown more particularly in Fig. 8 of the drawings to form a substantially rigid construction. Secured to the inner face of each of the plates 1 is a reinforcing plate 3 and extending through the plates 1 and 9 are the bolts Ill on which are mounted the sleeves II which hold the side plates 1 against inward movement and which reinforce the push beam constructions. At their forward ends the push beams are provided with the outwardly directed flanges l2 and to which is secured a scraping blade or mold board I3 having along its lower edge a knife like edge portion l4 as shown more particularly in Fig. 4 of the drawings. Secured to the inner face of each of the push beams 5 is an angle iron strip or bracket to which brackets is secured a plate I6 which extends transversely between the push beams 6. 'Also secured to the inner face of each of the push beams B is an angle iron bracket l1 and secured to these angle iron brackets is a transversely extending plate I 3 as also shown more particularly in Figs. 4 and 5 of the drawings. The plate I3 has the upwardly directed flange l3 and the downwardly directed flange 20, the upwardly directed flange i9 being secured to the blade or mold board l3 by means of rivets or other suitable fastenings and positioned between the inner face of the blade or mold board and the upturned flange I9 is a reinforcing plate 21. The downwardly directed flange of the plate 13 is secured to the plate l6 by means of rivets or other suitable fastenings and positioned between the face of the plate It and the outer face of the downwardly directed flange 20 is an upwardly directed flange 22 of a transversely extending plate 23 which in turn has a downwardly directed flange 24 secured to the plate 2! and blade or mold board l3 by means of rivets or other suitable fastenings, these rivets also securing in position the knife like cutting edge i4. From the above detailed description it will be noted that the push beams themselves are of strong construction and that the scraping blade or mold board I3 is secured to the push beams and reinforced so as to provide for the necessary strength while in use.

Secured to the bottom edge of each of the push beams 5, and just to the rear of the scraping blade or mold board is a runner 25 which is adapted to be engaged with the ground when the bulldozer is lowered into operative position.

Extending upwardly from the upper edge of each of the push beams 6, intermediate the ends thereof, is a standard 25 which is of hollow formation as shown more particularly in Fig. 3 of the drawings and the upper end of. which is opened to receive the lower end of a post 21, these posts 21 extending inwardly at an angle, as shown more particularly in Fig. 3 of the drawings, and being connected at their upper ends by the transversely extending plate or strip 23.

Secured to each of the track frames B and longitudinally spaced thereon are the brackets G and H, the brackets H, as shown more particularly in Figs. 7 and 10 of the drawings, including a base plate 23, secured to the track frame by means of the nuts and bolts indicated generally at 3|), the upwardly extending side plates 3| and the front plate 32. A block 33 is secured to the base plate 23 by one of the bolts and associated nut as shown more particularly in Fig. 10

bolt and nut 4|.

of the drawings and extending transversely between the side plates 3l is a bolt 34. The ends of the spring F engage the upper face of the blocks 33 and are positioned beneath the bolts 34, as shown more particularly in Fig. 10 of the drawings. Each of the brackets G includes a base plate 35, upwardly extending side plates 33 and front plate 31. Pivotally mounted between the side plates 33 are the clamps 33 and 33 which engage the upper flanges of the track frame B as shown more particularly in Fig. 9 of the drawings and these clamp plates are drawn inwardly or into clamping engagement by means of the Secured to each pair of brackets G and H and extending upwardly therefrom is a standard 42 which has an outwardly directed flange 43 struck from each vertical edge and positioned between those flanges and the outer faces 32 and 31 of the brackets G and H respectively are the plates 44. Bolts extend through the front faces 32 and 31 of the brackets G and H, through the flanges 43 and plates 44. and receive the nuts 46. By this arrangement it will be seen that the standards 42 are secured to the brackets G and H, that the brackets H form ready means for connecting the ends of the transverse spring F to the track frames B and that through means of the clamps 33 and 39 the brackets G may be easily secured in position and adjusted as desired.

Pivotally connected to the upper edge or surface of each of the standards 42, by means of a universal joint is one end of a cylinder 41 and positioned and operable in each of the cylinders 41 is a piston having a piston rod 48, the ends of the piston rods being pivotally connected to the posts 21 by means of universal Joints as shown more particularly in Fig. 3 of the drawings. It will thus be seen that the cylinders are connected to the standards 42 which are connected in turn to the track frames 13 while the pistons are connected to the posts 21 which in turn are connected to the push beams of the bulldozer.

Oil is adapted to be fed or forced into opposite ends of the cylinders 41 and on opposite sides of the pistons operable therein. This oil is normally stored within the tank 43 which has extending therethrough a tube forming a passage for the pipe 5| which has one end connected to a pump 52 through means of the pipe 53. Leading from one end of the tank 43, and communicating therewith, is a pipe 54 which in turn is connected to the pump 52 through means of the pipe 55 and branch 56. The pump 52 is operated from the tractor, in the usual wellknown manner, and draws the oil from the tank 49 through the pipes 54 and 55 and branch 55 and forces it through the pipes 53 and 5| into and through the pipe 51 into a valve casing indicated generally at 53 and in which is positioned a valve which is operable through means of the handle or lever 59 for controlling the movement of the oil in the various directions and through the various pipes desired. Oil is conveyed back from the valve casing 58 into the tank 43 through the pipe 60 and branch 5i. The valve casing 53 u is provided with the downwardly extending nipples or outlets 62 and 53. Leading from the nipple or outlet 32 is a short pipe section 54 connected to the T-coupling 55 and connected to and leading from this T-coupling is a downwardly extending pipe 65 with its lower end connected to and communicating with the T-coupling 31 from opposite sides of which lead the pipe sections 33 and 83 to the outer ends of which are connected the flexible piping Ill leading into the lower ends of the cylinders 41. When the valve within the casing 58 is set to allow passage oi the oil to the nipple or outlet 62 the oil is Leading from the nipple or outlet 63 is a pipe section H to the lower end of which is connected by means of the couplings l2 and 13 a pipe 14 having its lower end connected to and communicating with the T-coupling 15 from opposite sides of which extend the pipe sections" and 11 which are in turn connected to and communicate with the flexible tubing or piping 18 leading into and communicating with the upper ends of the cylinders 41, Within the pipe section 71 is positioned a relief valve indicated generally at T9 and leading from this relief valve is a pipe 80 connected by means of the coupling 8| with the pipe section 82 which in turn is connected by the pipe 83 to the T-joint 65 connected to the outlet nipple 62 by the pipe section 64. When the valve Within the casing 58 is set to communicate with the outlet nipple 63 oil will be conveyed through the pipes II and ll to the coupling 15 and from this coupling through the upper ends of the cylinders 41. The pressure of oil within the upper ends of the cylinders will force the pistons duwnwardly to lower the bulldozer into the position shown more particularly in Fig. 2 of the drawings with the lower or cutting edge of the scraping blade or mold board in contact with the ground. The relief valve 19 is provided to prevent breakage of parts should the pressure become too great in the lowering movement. If the pressure becomes too great the relief valve 19 is operated to permit passage of the same time I wish to call particular attention to the fact that the cylinders 41 are positioned so that a straight line through the cylinders would into the position shown in Fig. 2 of the drawin s. or in other words into operative position, t 1e lever 59 will be operated to position the valve within the casing ll to convey oil under pressure through the various connections into the upper ends of the cylinders 41. The oil entering the upper ends of the cylinders 41 under pressure causes the pistons within the cylinders to move 48 drawing downwardly on the posts 2'! which are connected lowered position through means of the transversely extendng spring F. It will be noted that going over uneven ground. without affect ng the position of the bulldozer. when one of the track frames and assoc'ated track is swung on its pivot the cylinder connected When going over uneven ground, as previously stated, the bulldozer will be permitted to float and will not be locked in permanent position. In other words the bulldozer will only be locked when the machine is being moved over even ground.

Having fully described my invent on what I claim as new and desire to secure by Letters Patent is:

1. A machine of the character described including in combination with a tractor hav'ng track frames, push beams pivotally connected to the track frames, a road implement carried by the for raising and lowering the push beams and road implement carried thereby, the center line through the cylinders extending to a point central of the tracks.

push beams pivotally connected to the track frames, a road implement carried by the push beams. members carried by the push beams carried thereby.

3. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to It can be seen that the track frames, a road implement carried by the push beams, members carried by the push beams and extending upwardly therefrom, members carried by the track frames and extending upwardly therefrom, and cylinders and pistons interposed between the members carried by the track frames and the members carried by the push beams for raising and lowering the push beams and road implement carried thereby.

4. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames, a road implement carried by the push beams, spaced brackets carried by the track frames, members carried by the brackets and extending upwardly therefrom, and means carried by the upwardly extending members for raising and lowering the push beams and road implement carried thereby.

5. A machine of the character described including in combination with a tractor having track frames and a transversely extending spring, push beams pivotally connected to the track frames, a road implement carried by the push beams, longitudinally spaced brackets connected to each of the track frames, one of said brackets connected to each of the track frames being formed and adapted to engage an end of the transversely extending spring, members carried by the brackets and extending upwardly therefrom, and means carried by the upwardly extending members for raising and lowering the push beams and road implement carried thereby.

6. A machine of the character described including in combination with a tractor having track frames and a transversely extending spring, push beams pivotally connected to the track frames, a road implement carried by the push beams, longitudinally spaced brackets connected to each of the track frames, one of said brackets connected to each of the track frames being formed and adapted to engage an end of the transversely extending spring and the other of said brackets being readily adjustable longitudinally of its track frame, members carried by the brackets and extending upwardly therefrom, and means carried by the upwardly extending members for raising and lowering the push beams and road implement carried thereby.

'7. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames, a road implement carried by the push beams, longitudinally spaced brackets connected to each of the track frames, one of said brackets being readily adjustable longitudinally of its track frame, members carried by the brackets and extending upwardly therefrom, and means carried by the upwardly extending members for raising and lowering the push beams and road implement carried thereby.

8. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames, 8. road implement carried by the push beams, longitudinally spaced brackets connected to each of the track frames, one of said brackets including clamping plates adapted to be engaged with the track frame, members carried by the brackets and extending upwardly therefrom, and means carried by the upwardly extending members for raising and lowering the push beams and road implement carried thereby.

9. A machine of the character described including in combination with a tractor having track frames, push beams on opposite sides of the frames and having upright arms and pivotally connected to the track frames, a road implement carried by the push beams, a pair of cooperating and communicatlvely connected hydraulic rams each interposed between said track frames and said upright arms of the push beams respectively for raising and lowering the push beams by hydraulic pressure, and means for relieving the pressure of the hydraulic means when the road implement engages the ground.

10. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames, at road implement connected to the outer ends of the push beams, a member extending between the push beams and connected to the inner faces thereof to the rear of the road implement, and a reinforcing member extending between and connected to the push beams between the road implement and the first mentioned member and connected to the road implement and first mentioned member.

11. A machine of the character described, including in combination with a tractor having track frames, side push beams pivotally connected to the track frames, a road implement carried by the push beams, and hydraulic means for pivotally raising and lowering the push beams, said hydraulicmeans including a pair of hydraulic cylinders and pistons operatively establishing hydraulic connection between each of said push beams and their corresponding track frames at points forward of the tractor axle, said pair of hydraulic cylinders being communicatlvely interconnected and with their associated pistons operatively functioning to permit movement of said track frames in going over uneven ground without affecting the position of the push beams and road implement relative to their horizontal side to side alignment with the tractor body.

12. A machine of the character described, including in combination with a tractor having track frames, side push beams pivotally attached to the track frames, a road implement carried by said push beams, and hydraulic means including a pair of transversely spaced hydraulic rams respectively establishing operative hydraulic connection between each of said push beams and their corresponding track frames, said connections being established at points forward of the tractor axle, and said pair of hydraulic rams being communicatlvely inter-connected and operatively functioning to permit said rams and the frames respectively connected therewith to move alternatively up or down or move together up or down, thus to permit movement of said track frames in going over uneven ground without affecting the position of the push beams and road implement relative to their horizontal side to side alignment with the tractor body.

13. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames, a road implement carried by the push beams, and hydraulic means interposed between the track frames and push beams for raising and lowering the push beams, said hydraulic means operating to permit movement of the track frames in going over uneven ground without affecting the position of the push beams and road implement carried thereby relative to the tractor.

14. A machine of the character described inscluding in combination with a tractor having track frames, push beams pivotally connected to the track frames at opposite sides of the tractor, a road implement carried by the push beams, and a hydraulic ram interposed between each of the track frames and a push beam, hydraulic rams being operable to raise and lower the push beams and to permit independent movement of the track frames in going over uneven ground without affecting the position of the push beams and road implement carried thereby relative to the tractor.

15. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames at opposite sides of the tractor, a road implement carried by the push beams, a hydraulic ram interposed between each of the track frames and a push beam, and fluid passages connecting the rams, said hydraulic rams being operable to raise and lower the push beams and with their connecting passages permitting independent movement of the track frames in going over uneven ground without affecting the position of the push beams and road implement carried thereby relative to the tractor.

16. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the track frames, a road implement carried by the push beams, members extending upwardly from the push beams, means connecting the upwardly extending members, and hydraulic means interposed between the track frames and upwardly extending members of the push beams, said hydraulic means operating to permit movement of the track frames in going over uneven ground without affecting the position of the push beams and road implement carried thereby relative to the tractor.

17. A machine of the character described, ineluding in combination with a tractor having track frames, side push beams pivotally connected to the tractor, an implement carried by the push beams, and fluid pressure means for positively raising and lowering the push beams, said fluid pressure means including a pair of fluid pressure cylinders and pistons operatively establishing fluid connection between each of said push beams and their corresponding track frames, said pair of fluid pressure cylinders having the same ends thereof in fluid intercommunication to equally distribute fluid pressures on the same sides of their associated pistons for allowing relative up and down movement of said track frames in going over uneven ground without affecting the position of the push beams and implement relative to their horizontal side to side alignment with the tractor body.

18. A machine of the character described, including in combination with a tractor having track frames, push beams pivotally attached to the tractor, an implement blade carried by said push beams, and fluid pressure means including a pair of transversely spaced fluid pressure rams respectively establishing operative fluid pressure connection between each of said push beams and their corresponding track frames, said connections being established at points forward of the tractor axles, and said pair of fluid pressure rams being communicatively interconnected and operatively functioning to permit said rams and the track frames respectively operatively connected therewith to move alternately up or down or to move together up or down, thus to permit movement of said track frames in going over uneven ground Without affecting the position of the push beams and road implement relative to their horizontal side to side alignment with the tractor body.

19. A machine of the character described including in combination with a tractor having track frames, push beams pivotally connected to the tractor, a. road implement carried by the push beams, and a separate double acting fluid pressure ram establishing fluid pressure connection between each of the track frames and a push beam, to positively raise and lower the push beams relative to the tractor, the same ends of said fluid pressure rams being in fluid intercommunication to equalize pressures in the rams and to permit movement of the track frames in going over uneven ground without affecting the level position of the road implement relative to the tractor.

20. In a machine of the character described including a tractor, push beams pivotally connected to the tractor and a road implement carried by the push beams, the improvement which comprises a pair of fluid pressure rams operatively connecting the push beams and the tractor, and means for supplying fluid under pressure to both ends of the ram cylinders for positively moving the implement up and down relative to the tractor, said ram cylinders being communicatively interconnected to uniformly distribute fluid pressure therein irrespective of movement of the tractor in going over uneven ground.

21, In a machine of the character described including a tractor, push beams pivotally connected to the tractor and an implement carried by the push beams, the improvement which comprises a hydraulic ram on each side of the tractor operatively connecting the push beams and the tractor, means for supplying a. hydraulic fluid under pressure to both ends of the ram cylinders for positively moving the implement up and down relative to the tractor and means establishing fluid interconnection between said ram cylinders to uniformly distribute said fluid to the ram cylinders.

22. In combination, a tractor having a pair of independently movable track frames, a pair of push beams pivotally carried by said tractor, an implement blade carried by and extending between said push beams. and means to cause relative movement of said push beams and said track frames as the tractor moves over uneven ground, said means comprising a pair of fluid pressure jacks operatively connecting the push beams and track frames, and means establishing fluid intercommunication between the same ends of both jacks to equally distribute the fluid pressure therein.

23. A scraper comprising a frame structure including spaced side frame beams, means supporting said side frame beams above the ground, a scraper assembly in pivotal relation to said frame beams, a fluid pressure operated jack operatively connecting one side of said scraper assembly with the frame beam on said side, a second fluid pressure operated jack operatively connecting the other side of said scraper assembly with the other frame beam, a fluid pressure supply line communicating with the same ends of both jacks to supply fluid under pressure thereto for operating the jacks to force the scraper downward against the ground whereby the same ends of both jacks are in fluid intercommunication and fluid will flow freely between the jacks to equalize the applied pressures on both sides of the scraper and means for supplying fluid under pressureto the other ends of the jacks for raising the scraper relative to the frame.

24. A scraper comprising a frame structure, a scraper assembly mounted for vertical movement relative to said frame structure, a fluid pressure operated jack operatively connecting one side of said scraper assembly with one side of the frame, a second fluid pressure jack operatively connecting the opposite side of the scraper assembly with the other side of the frame, a supply line communicating with the same ends of both jacks to supply fluid under pressure thereto for operating the jacks to force the scraper downwardly, a second supply line communicating with the opposlte ends of both jacks to supply fluid under pressure thereto for operating the jacks to lift the scraper' upwardly whereby the same ends of bothiacks are in fluid intercommunication and .fluid can flow freely between the jacks.

25. A scraper comprising a frame structure ini eluding spaced side frame beams rneans supporting said frame beams above the ground, a scraper assembly in pivotal relation to said frame beams, a fluid'pressure operated jack operatively connecting one side of the scraper assembly with the frame beam on said side, a second fluid pressure operated jack operatively connecting the other side of said scraper assembly with the other frame beam, and a fluid pressure supply line communicating with the same ends of both jacks to supply fluid under pressure thereto for operating the jacks whereby the same ends of both lacks are in fluid lntercommunication and fluid 5 will flow freely between the jacks to equalize the applied pressures on both sides of the scraper even when the frame beams are at different levels in going over uneven ground.

26. In a bulldozer including a tractor and an implement assembly movably carried by the tractor, the improvement which comprises a pair of fluid pressure rams operatively connecting the assembly with the tractor for raising and lowering the assembly relative to the tractor, means in fluid intercommunication for supplying fluid under pressure to the same ends of both rams, additional means in fluid intercommunication for supplying fluid under pressure to the other ends of said rams, and a single valve communicating with said means to control fluid flow therethrough, said means operating said rams to move the implement up and down relative to the tractor while the fluid pressures in the same ends 01' both rams are equalized to uniformly distribute the load between the rams.

27. In combination, a tractor and an implement assembly connected with said tractor for up-and-down movement relative thereto, a pair of fluid pressure rams operatively connecting the implement assembly with the tractor, and means for supplying fluid under pressure to both ends of the ram cylinders for positively moving the implement up and down relative to the tractor, the same ends of said ram cylinders being cornmunicatively interconnected to uniformly distribute fluid pressure therein whereby fluid can flow between the cylinders in response to variations in loads on the rams for holding the implement level.

28. In combination, a tractor, push beams pivotally mounted on the tractor, an implement blade carried by the push beams, a pair of fluid pressure jacks operatively connecting the push beams and the tractor to swing the beams for raising and lowering the implement blade. means establishing fluid intercomrnunication between the same ends of both Jacks to equally distribute fluid pressure therein, and a single valve communicating with said means to control fluid flow therethrough, said valve, in one position thereof, allowing free fluid flow therethrough to float the push beams and implement blade.

29. In a machine of the character described, including a tractor and a movable assembly carried by the tractor, the improvements which comprise a pair of fluid pressure rams operatively connecting the assembly with the tractor for 0 raising and lowering the assembly relative to the tractor, means in fluid intercommunication for supplying fluid under pressure to the same ends of both rams, additional means in fluid intercommunication for supplying fluid under pressure to the other ends of said rams, and a single valve communicating with said means to control fluid flow therethrough, said valve adapted to supply fluid to said same ends of the rams for raising the assembly, to supply fluid to said other ends of the rams for lowering the assembly. and to allow free fluid flow therethrough to float the assembly, whereby the fluid pressures in the same ends of both rams are always equalized to uniformly distribute the load between the rams.

HARRY C. BUF'FINGTON.

DISCLAIMER Re. 20,996.Har1'y C. Buflington, Springfield, Ill. SCRAPER on GRADER. Patent dated Feb. 7, 1939. Disclaimer filed Jan. 23, 1946, by the assignee, The Baker Manufacturing Company. Hereby enters this disclaimer to claims 20, 21, 23, 24, 25, 26, 27, 28, and 29 of said patent.

[Ofiicial Gazette Alarch 5, 1946.] 

